Continuous venovenous hemofiltration improves arterial oxygenation in endotoxin-induced lung injury in pigs

Background: Hypoxemia is common in septic acute lung failure. Therapy is mainly supportive, and most trials using specific inhibitors of key inflammatory mediators (ie., tumor necrosis factor a, interleukin 1) have failed to prove beneficial. The authors investigated if a nonspecific blood purification technique, using zero-balanced high-volume continuous venovenous hemofiltration (CVVH), might improve arterial oxygenation in a fluid-resuscitated porcine model of endotoxin-induced acute lung injury Methods. Piglets of both sexes weighing 25-30 kg were anesthetized and mechanically ventilated. After baseline measurements, animals received an intravenous infusion of 0.5 mg/kg endotoxin (Escherichia coli lipopolysaccharide). One hour after endotoxin, animals were randomly assigned to either treatment with CVVH (endotoxin + hemofiltration, n = 6) or spontaneous course (endotoxin, n = 6). At 4 h after randomization, animals were killed. Hemofiltration was performed from femoral vein to femoral vein using a standard circuit with an EF60 polysulphone hemofilter. Results. Endotoxin challenge induced arterial hypoxemia, an increase in peak inspiratory pressure, pulmonary hypertension, and systemic hypotension. Treatment with CVVH did not improve systemic or pulmonary hemodynamics. However, arterial oxygenation was increased in endotoxin-challenged animal at 5 h after completion of endotoxin infusion, as compared with animals not receiving CVVH (arterial oxygen tension, 268 +/- 33 vs. 176 +/- 67 mmHg, respectively, P < 0.01). In addition, treatment with CVVH attenuated the endotoxin-induced increase in peak inspiratory pressure and increased lung compliance. Conclusion: These results suggest that nonspecific blood purification with high-volume CVVH improves arterial oxygenation and lung function in endotoxin-induced acute lung injury in pigs, independent of improved hemodynamics, fluid removal, or body temperature.